When a pair of circuit breakers are connected to separate power systems, it is critical that both power systems are not connected to a common load at the same time. This is especially true, for example, when a utility power source is connected to a load through a first circuit breaker and an auxiliary power supply, such as a local generator, is connected to the same load through a second circuit breaker. Interlock devices are required which will allow only one of the interlocked circuit breakers to be on the ON condition such that the other circuit breaker must remain in its OFF position. Such interlock arrangements are also used with electric switches for essentially the same purpose.
U.S. Pat. No. 3,319,020 describes a sliding interlock arrangement for preventing one circuit breaker from being turned ON while the other circuit breaker is in its ON position. U.S. Pat. No. 3,312,797 describes a cam interlock arrangement for interlocking between a pair of circuit breakers connecting with a common load. U.S. Pat. No. 3,778,633 is an example of a "walking beam" interlock arrangement where the circuit breaker operating mechanisms are interlocked rather than the circuit breaker operating handles. U.S. patent application Ser. No. 205,894 filed June 13, 1988 now U.S. Pat. No. 4,827,089 entitled "Molded Case Circuit Breaker Interlock Arrangement" describes a pair of molded case circuit breakers that are interlocked by means of the operating mechanism crossbars to insure that only one of the interlocked circuit breakers can be turned on at one time.
Circuit breakers are also operated from a remote location by means of a motor operator whereby a remote switch connects to the motor operator that is arranged on the surface of a cabinet-mounted circuit breaker. The aforementioned interlock arrangements do not readily provide means for interlocking between a pair of circuit breakers when one of the circuit breakers is controlled by a remote motor operator such as that described within U.S. Pat. No. 3,171,920. U.S. Pat. No. 3,778,633 describes a specific interlock arrangement for a pair of motor operators, each motor operator controlling a separate one of a pair of circuit breakers.
A rotary switch operator is a device that is mounted on the handle of a circuit breaker or electric switch to transfer the ON - OFF motion of the circuit breaker handle from transilational to rotary operation. U.S. Pat. No. 3,206,585 describes one such rotary switch operator. The aforementioned U.S. patents that represent the state of the art of interlock devices do not readily provide for interlocking between a pair of circuit breakers when one of the circuit breakers supports a motor operator device. U.S. Pat. No. 4,295,054 describes an interlock arrangement used with a pair of circuit breakers wherein each circuit breaker supports a rotary switch operator.
One purpose of the instant invention is to provide a universal interlock arrangement for conveniently interlocking between circuit breakers and electric switches when either of the circuit breakers or electric switches is controlled by a motor operator or a rotary switch operator.